1️⃣ Melting Points & Thermal Gradients • Aluminum (Al) melts at ~660 °C • Bronze (Cu-Sn alloy) melts between ~950–1200 °C depending on composition If bronze is already molten, it’s significantly hotter than the aluminum being poured. That temperature difference creates violent heat transfer, driving convection currents at the interface. Heat flows from the hotter bronze to the cooler aluminum. This rapid thermal exchange creates surface turbulence and instability. ⸻ 2️⃣ Density Controls the Motion • Aluminum density ≈ 2.7 g/cm³ • Bronze density ≈ ~8.7 g/cm³ Because aluminum is much less dense, it floats instead of sinking. That floating layer becomes unstable due to: • Buoyancy-driven flow • Convection currents • Surface tension gradients (Marangoni effect) This is why you see spirals, cracking textures, and dynamic swirling patterns. ⸻ 3️⃣ Oxidation & Color Formation Molten aluminum oxidizes almost instantly in air, forming aluminum oxide (Al₂O₃). That ultra-thin oxi...